Question: 7 markers cost $9.80. Which equation would help determine the cost of 2 markers?
There are several equations that could help determine the cost, each with a slightly different approach. We can write the fact that 7 markers cost $9.80 as a proportion: $\dfrac{7}{\$9.80}$ Let $x$ represent the unknown cost of 2 markers. Since 2 markers cost $x$ , we have the following proportion: $\dfrac{2}{x}$ The cost changes along with the number of markers purchased, and so the two proportions are equivalent. $\dfrac{7}{\$9.80} = \dfrac{2}{x}$